Stitch-forming mechanism for sewing-machines.



G. J. SIBBALD.

STITCH FORMING MECHANISM FOR SEWING MACHINES. APPLICATION FILED MAR. 12, 1908.

1, 1 1 8,450, Patented Nov. 24, 1914.

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G. J. SIBBALD.

STITCH FORMING MECHANISM FOR SEWING MACHINES.

APPLICATION TILED MAR. 12, 1008.

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APPLICATION FILED MAIL 12, 1908.

1,118,450, Patented Nov. 24, 1914.

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r Specification of Letters Patent;

STITCH-FORMING MECHANISM FOR SEWING-MACHINES.

Patented Nov. 24, 1914.

' Application filed March 12, 1908. Serial No. 420,609.

To all'whom it may concern:

Be it known that 1, CHARLES J. SIBBALI),

a citizen of 'thelUnited States, of Waterford, in the county of: Albany and State of New York, have invented certain new and useful Improvements in Stitch-Forming Mechanism for Sewing-Machines; and I hereby declare that the following is a full,

. Another object of this invention is to so construct stitch forming means for sewing machinesthat the needle thread, carried downward by an initial stroke of the needle may be so engaged'that its movement toward the work is resisted while loops successively' formed in said needle thread are passed around such engaged portion and, so'such' portion is permitted to be drawn, by'

the,said s'uccessive loops, into or against the work.' 4

Another object of this invention is to so construct stitch .formin means for sewing 86 machines that theneed e'thread carried toward the looperhy an initial stroke of the needle may befrietionally engaged and that sufiicient thread may be drawn 1 from the needle; thread supply to: provide an under thread supplyfor thesewmg operation.

Thefinvention consists in the" eculiar features of construction and com ination of parts hereby th Objects of the invention are carried into efi'ect as shall hereinafter 45..b'e morefully described and pointed out in the claims.

Figure 1, represents an elevation, partly in section, of portions of a sewin machine illustrating'thenew invention. *1g. 2, rep.-

50,-. esents asec'tionalaview thereof taken on ine 2 -2 Fig. f1. .Fi' 3, represents a view similar .'to parts of ig. 1 to illustrate the engagement ofithe end portion of, the needle thread by the hook, parts-of the machine being shown in section. Fig. 4, 'represents ,a'view taken at ight anglesto F g. 3. Fig.-

5, represents a bottom plan view of the machine showing the hook driving means and the means for effecting the opening of the thread clamping device Fig. 6, represents a view of the thread clamping device and the hook, in which view the hook is shown as drawing down the end portion of the needle thread to provide an under thread supply and to draw said thread intothe clamp. Fig. 7, represents a sectional view of the clamp and the hook, the clamp being held in the open position as when the thread is in position shown in Figs. 6 and 8. Fig. 8, represents the parts shown in Fig. 6 with the cut end of the needle thread drawn between the parts of the thread clamp. Fig.

9, is a top plan view of the clamp with its hinged member closed to engage the needle thread when said thread is carried to or approximately to the position shown in Fig; 8. Fig. 10, represents a viewof the parts shown in Fig. 8, with the hook positioned to cast off a loop of the needle thread around the held portion of the'same thread. Fig. 11, represents the stitch formed by this mechanism in continuous sewing.

correspondingv parts throughout.

As shown in the drawings, in its preferred form 15 represents the usual needle bar of any ordinary sewing machine, the operating parts of which are well known, an'd'16 is the needle to which the thread a -b is supplied in the ordinary manner.

The bed plate 17 has the usual opening 18 above which extendsv the throat plate 19..

having the needle hole 20. At the under side of the bed plate is journaled the drive shaft 21 adapted to be driven in any ordinary manner and having the worm 22 and Similar, numbers of reference designate a riving connection with the journaled shaft of the bevel gear 23. Motion is transniitted from the gear 23 by means of the idle gear 2-1 to the gear 25 mounted on' the tubular hook-driver-shaft 26 which is journaled in bearings and has the usual hook driver 27 rotatable within the casing'28 and engaged in the ordinary and well known manner with the hook 29 rotatablv supported within said casing. The plate 30 of said hook 29, has the axially d is posed perforated hub 31 having the 're duced portion 32, Figs. 2 and 7, furnished with a screw threaded 'bore into which the.

perforated reduced shank of the perforated button 33 is screwed. The reduced portion or neck 32 0f the hub 31. is rotatably enigaged in the collar 34 of the clampmember 35, and is held from longitudinal movement therein between the button 33 and the larger diameter of said hub. Said clamp member 35 has a central chamber, to receive said buti ten 33, and is. furnished with the pin sock-. ets 36' and 37 and lip 38.r And hinged to said "member by a spring closed hinge,

Fig. 9, is the complemental clamp member 39 having the pins 40.-41 on its inner face, adapted to be received by the sockets 36 and 37,- and, on its outer face the pin 42 while in ascrew thread perforationin said member 39 is engaged the screw 43. Within aailaceo that in lock stitch sewing it is necessary to supply sufficient under thread, for the numberof stitches to be sewn and itisto be pre-L' the bore. of the buttonsl33 is movable the. plunger 44 having a reduced portion which 7 extends into the bore of :the hub 31.

The thread clamping "device and its 061- lar 34 is held from rotation by the arm 45 pivotally-mounted on the lower part of the casing and having fingers 46 at its free end which engage the pin42 of the clamp member 39, theusual latch 47 being providedon said casing 28 to lock the arm 45 in the position forengaging said pin 42. On the upper part of said casing or other fixed part of the machine is mounted the pin 48 which extends toward-theupper end of the clamp member 35 and hence extends above the.

path of the hook.

In the perforatlon of theshaft26'is slidably mounted the rod 49 having an extension which is free to enter the perforation of the hub 31, see Figs. 2 and 7," to act sumed that the length of theunder thread or its equivalent herein referred to. as such, w

is sufficient 'for the sewing operation under consideration. i

Before the sewing operation the thread a is drawn throughthe needle to provide the end I) as is usual toprevent the'end of the g thread from drawing back through the eye of the needle on the first downward stroke considerably longer than usual.

The mechanism is so timed as to its opera- (w of the'needle; this end 5 may however be ,t'ion that as the initial downward movement of the needle is made. the cam 53 acts on the bearing 54 of the lever 55 to swing said lever and force inward the rod 49 the reduced-- portion of which pressesforward the plun- 1 ger 44 which effects the swinging outward against the plunger 44, when this rod49 is forced inward against the action of its retracting spring 50. located on said rod between a cross pin fixed to the rod and a fixed portion of the machine. -Means are provided for intermittently sliding said rod. 49

inward against the action of the spring 50 to press forward the vplunger 44 against the clamp member 39 whereby said member is swung outward from its complemental mem- "ber 35 againstthe closing pressure of its the highest closing spring. Such means are shown in Fig. 5 of the drawing and preferably comprise the usual button'cla np vibrator cam- 51 journaled on a stud extending from'the bed plate of the machine and having the gear 52, meshing with the. worm 22 of the main shaft, and'the cam 53 so adjustably. mounted on the cam 51 that, at a'predej termined point in the sewing operation or initial thereto, said cam 53 is brdilght to position to'act on the bearing 54 of'the bell crank against the .outer endofthe rod 5'0 whereby at such predetermined point said rod 50 is pushed inward to actuate the plunger 44 iever 55 which is pivotally mounted in the machine and has 'a' member which bears and is held inward during the movement of bearing 54.

portion of theacam 53 past the I "the clamp member 39 under the tension of ma ofthe'clamp member 39 against the action of its closing spring. When now the needle has moved down approximately to the'point shown in Fig. 3 the ook 29 engages the loop of the end 6 of the thread a and, in the movement of saidhook, draws on said'=loop, 'opening said loop and draw1ng' it downward. Under said drawing action of the hook the thread a 'is also somewhat drawn 1% 'down throughthe eye of the needle unless the tension on said thread is more than suiii 'cient to overcome the frictional resistance of the work, through which the end 5 is drawn, on said end. After. the engagement of the m hook 29 with a loop of the thread said hook .first carries the loop toward the spreader 48 which guides one arm of said thread loop back of the hook carrier. This feature being of more'particular importance to the 3 5,.

second and subsequent loops than to the first loop as will hereafter be explained.

The continued rotation, or movement, of

'the'hook 29 now efi'ects the drawing of the end 6 of the thread downward as is shown 29 in Fig. 6 and over the extension 38 of the clamp member 35 which assists in guiding said thread 7) betweenthe clamp members 35 and 39, approximately as shown'in Fig. 8; at which time said thread is intercepted 12a by- Ithe.pin 41 of said, clamp. At or about this time the cam 53 passesthe'bearing 54 f,of thelever 55. and the spring 50 acts to retracttiie rod 49 and permit the closing of der tension thereby.

At the second and subsequent'downward -movements of the needle the thread loos .taken by the hook 29 iscarried around sai clamp one arm of said loop being guided by the spreader 4.9 back' of the hook carrier 30 passes between the ends of the plunger 44 and rod 49. These successive loops pass around the thread clam in'g deviceas indicated in Fig. 10*and, remapproximately thepoint indicated in said figure, are cast off and are drawn upward by the usual and well known thread take up and the upward movement of the needle until said loops are drawn around the thread extending from the work to the clamp and said drawling action is preferably continued until the thread held under tension by said clamp is drawn out sufiiciently to form its part of the stitch, and the sewing operation proceeds as in any ordinary sewing machine supplied with upper] and under thread.

For, in effect, the thread clamp -39 assumes the function of an under thread holder and yields said thread as thestitches are formed in succession.

- It is to be noted that the thread clamping device 35-39 is preferably held fromrotation, during the sewing of the second and subsequent stitches, by means of the arm having its fingers 46 engaging thepin 42 of the clamp member 39, but this invention is notfnecessarily limited thereby to such a thread clamping means held "from movement for-if the arm 4 5 was released from the in 42, after the closing of said clamp the rictional'engagement of the hub 32' on the collar 34 of saidclamping device would tend to rotate s'aid clamp and efi'ect the" drawing downward of an-additiona'l-supply of. under thread which would be wound around the clamp. But it"is-apparent'that the preferred means 'for drawin downward of the needle thread tofurnis am under thread supply is' through the mediumof the hook moving with respect tothe clamp.

The term hook is herein-used as particularly' vdescriptive of the device shown but reference to such term includes any device of' this-nature'however o erated which acts to draw the thread in or; er to assist in forming a loop or for the purposeof drawing down the needle thread to provide a lmiper.

' Iaving thus described claim as new and desire to secure by Letters Patent.

. 1. Stitch forming means for sewing machines comprising a needle, a spring closed thread clamp located below the needle,

means actuated by the driving meansfor opening said clamp and for permitting, it to close after a period of time, and a looper hook rotatable with respect to said clamp.

my I invention I ,2. Stitch forming means for sewing machines comprising a rotatable loop'er, a thread clamp located below'the work and .having a spring closed'member extending a approximately to the path of said looper,

means operated through the driving mech-' anism for opening said member against its spring, said means including a member adapted to be retracted before the formation of a closed loop. a 3. Stitch forming means for sewing machines comprising a thread clamp a looper journaled in a bearing in said clamp and carrying clamp opening means, means for holding said clamp from movement, and means for actuating said clamp opening means.

4. Stitch forming means for sewing machines comprising a twopart spring clamp having a collar, a perforated hub journaled in said collar, a clamp opening plunger slidable in said perforation, a loop hook mounted on said hub, means for holding the clamp from movement, and means for actuating said plunger at times'rto open the clamp. 5. Institch forming means for sewing machines, a thread clamp comprising one member furnished with a bearing and having a thread guiding lip at itslower portion, and a member hinged to said first member and having a sprlng acting to close the same and CHARLES J. SIBBALD Witnesses:

' H. J. Mnlnnn, v M. M. HARRINGTON. 

